The invention relates to methods and apparatus for reducing frictional force between a piston and a cylinder in an engine, compressor, or the like, and relates more specifically to methods and apparatus for balancing lateral component of force imparted to a piston from its connecting rod to reduce such friction.
It is well-known that in reciprocating piston engines and compressors, the force imparted to the piston by the connecting rod has a horizontal component that force the walls of the piston against one side or the other of the cylinder wall, thereby increasing frictional forces. (Piston friction is thought to be a combination of dry (metal on metal) friction and fluid dynamic drag (assuming there are some traces of fluid between the piston and cylinder wall, such as oil). It is also thought that dry friction is the predominate component.) Such horizontal component of force is present for all orientations of the crankshaft except those in which the connecting rod is precisely vertical. Various efforts have been made to reduce such increased frictional forces. The state-of-the-art is generally shown by U.S. Pat. Nos. 2,802,706, 3,035,879, 3,058,792, 3,137,439, 3,906,923, 4,058,104, 4,111,104, 4,158,328, and 4,508,019 and U.K. Pat. No. 194,959, French Pat. No. 1,221,170, and German Pat. No. 2,031,091. Of the above references, U.S. Pat. Nos. 4,058,104 and 4,111,104 and British Pat. No. 194,959, French Pat. No. 1,221,170 and German Pat. No. 2,031,091 disclose the concept of using compression gas pressure from the cylinder to pass through a wall of the piston and produce a lateral counterforce against the cylinder wall, reducing friction caused by lateral forces on the piston. None of the prior art known to me discloses a practical apparatus for reducing frictional force between a piston and cylinder by accurately balancing the lateral force produced on the piston by the connecting rod thereof. If a practical, reliable structure could be provided that effectively offsets such lateral forces, reduced engine wear, and improved fuel economy could be achieved in internal combustion engines. Reduced wear could be achieved in compressors.